vty: Fix typo testing return value of bind

Thanks to playya__ (Dr. Fred) on IRC for pointing this out

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/src/vty/telnet_interface.c b/src/vty/telnet_interface.c
index 1523a89..098fa2e 100644
--- a/src/vty/telnet_interface.c
+++ b/src/vty/telnet_interface.c
@@ -70,7 +70,7 @@
 	sock_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
 
 	rc = bind(fd, (struct sockaddr*)&sock_addr, sizeof(sock_addr));
-	if (bind < 0) {
+	if (rc < 0) {
 		LOGP(0, LOGL_ERROR, "Telnet interface failed to bind\n");
 		close(fd);
 		return rc;